Soapbox Science 2022

Soapbox Science 2022

A l’occasion de l’événement Soapbox Science, Maria De La Fuente Ruiz – Service Biogéochimie et Modélisation du Système Terre (BGEOSYS) – expliquera pourquoi le changement climatique n’est pas uniquement lié au CO2.

Le 25 juin 2022 de 12:00-18:00, Place de la Bourse à 1000 Bruxelles

Chaque année, la plateforme Soapbox Science organise des événements à travers le monde durant lesquels les espaces publics, où ils prennent place, se transforment en arène d’apprentissage et de débat scientifique.

À travers ces rencontres entre le public et les scientifiques, la plateforme a également la volonté de donner une visibilité aux femmes et personnes non-binaires et de lutter contre les inégalités entre les sexes qui subsistent dans le domaine scientifique.

Cette année, l’événement marque une halte àBruxelles et comptera sur la participation de Maria De La Fuente Ruiz, chercheuse postdoctorale au sein du groupe BGeoSyS de l’ULB.

Son intervention lors de l’événement Soapbox intitulée “Climate change is more than CO2” vise à sensibiliser aux différentes causes et effets du changement climatique qui, dans les médias, sont généralement simplifiés aux émissions de CO2 et aux changements de température mais qui sont en réalité beaucoup plus complexes et interdépendants. Selon elle, il est essentiel de familiariser la science du climat aux citoyens ordinaires pour qu’ils comprennent mieux l’urgence climatique que nous connaissons et que nous continuerons à connaître, et qu’ils agissent en conséquence.

Quant à l’objectif de Soapbox Science de donner davantage de visibilité aux femmes, Maria s’exprime:

“Je suis extrêmement heureuse de pouvoir porter la parole des femmes dans le domaine des sciences naturelles encore dominé par des figures masculines. J’ai été très active sur les médias sociaux et sur plusieurs projets parallèles (par exemple, une mer de femmes leaders ou le manifeste Fuerteventura) pour sensibiliser au changement climatique et à la durabilité et pour encourager les femmes à suivre leur passion dans le domaine scientifique.”

A propos de Maria De La Fuente Ruiz

Maria De La Fuente Ruiz a étudié une licence en géologie et un master en ingénierie géotechnique à Barcelone. Ensuite, elle a réalisé un doctorat en sciences océaniques (spécialisation dans la modélisation des hydrates de méthane) au National Oceanography Centre de Southampton (Royaume-Uni) où elle a eu l’opportunité de participer à plusieurs expéditions océanographiques en traversant l’océan Austral et l’Atlantique pendant plusieurs mois et en collectant des données pour observer les changements dans les propriétés physiques et chimiques des océans dus au changement climatique. En 2020, elle a lancé son projet “FIESTA” à l’ULB, supervisé par Sandra Ardnt (ULB), Héctor Marín-Moreno (NGI), et Tim A. Minshull (Université de Southampton).

A l’ULB, Maria étudie le puits benthique de méthane et les rétroactions benthiques entre le cycle du carbone et le climat en réponse à la dissociation des hydrates de gaz. Son travail vise à évaluer les émissions de méthane de l’océan émises par le climat et à examiner leurs effets environnementaux benthiques qui peuvent avoir un impact essentiel sur les rétroactions carbone-climat, les bilans régionaux de carbone inorganique dissous (DIC), l’acidification des océans, la désoxygénation et le déséquilibre des nutriments dans l’océan. Ce type d’investigation est un exemple clair de l’interconnexion des processus physiques et biogéochimiques qui peuvent alimenter le changement climatique et altérer la santé des océans dont la chimie est vitale pour tamponner les concentrations de carbone atmosphérique et l’augmentation de la température globale.

Recent publications

Recent publications

Energies - May 2022

Assessing the Benthic Response to Climate-Driven Methane Hydrate Destabilisation: State of the Art and Future Modelling Perspectives

Maria De La Fuente, Sandra Arndt, Héctor Marín-Moreno and Tim A. Minshull

Modern observations and geological records suggest that anthropogenic ocean warming could destabilise marine methane hydrate, resulting in methane release from the seafloor to the ocean-atmosphere, and potentially triggering a positive feedback on global temperature. On the decadal to millennial timescales over which hydrate-sourced methane release is hypothesized to occur, several processes consuming methane below and above the seafloor have the potential to slow, reduce or even prevent such release. Yet, the modulating effect of these processes on seafloor methane emissions remains poorly quantified, and the full impact of benthic methane consumption on ocean carbon chemistry is still to be explored. In this review, we document the dynamic interplay between hydrate thermodynamics, benthic transport and biogeochemical reaction processes, that ultimately determines the impact of hydrate destabilisation on seafloor methane emissions and the ocean carbon cycle. Then, we provide an overview of how state-of-the-art numerical models treat such processes and examine their ability to quantify hydrate-sourced methane emissions from the seafloor, as well as their impact on benthic biogeochemical cycling. We discuss the limitations of current models in coupling the dynamic interplay between hydrate thermodynamics and the different reaction and transport processes that control the efficiency of the benthic sink, and highlight their shortcoming in assessing the full implication of methane release on ocean carbon cycling. Finally, we recommend that current Earth system models explicitly account for hydrate driven benthic-pelagic …

link to the article

Nature - March 2022

The land-to-ocean loops of the global carbon cycle

Regnier P., Resplandy L., Najjar R.G. and Ciais P.

Carbon storage by the ocean and by the land is usually quantified separately, and does not fully take into account the land-to-ocean transport of carbon through inland waters, estuaries, tidal wetlands and continental shelf waters—the ‘land-to-ocean aquatic continuum’ (LOAC). Here we assess LOAC carbon cycling before the industrial period and perturbed by direct human interventions, including climate change. In our view of the global carbon cycle, the traditional ‘long-range loop’, which carries carbon from terrestrial ecosystems to the open ocean through rivers, is reinforced by two ‘short-range loops’ that carry carbon from terrestrial ecosystems to inland waters and from tidal wetlands to the open ocean. Using a mass-balance approach, we find that the pre-industrial uptake of atmospheric carbon dioxide by terrestrial ecosystems transferred to the ocean and outgassed back to the atmosphere amounts to 0.65 ± 0.30 petagrams of carbon per year (±2 sigma). Humans have accelerated the cycling of carbon between terrestrial ecosystems, inland waters and the atmosphere, and decreased the uptake of atmospheric carbon dioxide from tidal wetlands and submerged vegetation. Ignoring these changing LOAC carbon fluxes results in an overestimation of carbon storage in terrestrial ecosystems by 0.6 ± 0.4 petagrams of carbon per year, and an underestimation of sedimentary and oceanic carbon storage. We identify knowledge gaps that are key to reduce uncertainties in future assessments of LOAC fluxes.

link to the article

Nature Climate Change - February 2022

Deciphering the multiple effects of climate warming on the temporal shift of leaf unfolding

Haicheng Zhang, Isabelle Chuine, Pierre Regnier, Philippe Ciais and Wenping Yuan

Changes in winter and spring temperatures have been widely used to explain the diverse responses of spring phenology to climate change. However, few studies have quantified their respective effects. Using 386,320 in situ observations of leaf unfolding date (LUD) of six tree species in Europe, we show that accelerated spring thermal accumulation and changes in winter chilling explain, on average, 61% and 39%, respectively, of the advancement in LUD for the period 1951–2019. We find that winter warming may not have delayed bud dormancy release, but rather it has increased the thermal requirement in reaching leaf unfolding. This increase in thermal requirement and the decreased efficiency of spring warming for thermal accumulation partly explain the weakening response of leaf unfolding to warming. Our study stresses the need to better assess the antagonistic and heterogeneous effects of winter and spring warming on leaf phenology, which is key to projecting future vegetation–climate feedbacks.

link to the article

Ocean Science - January 2022

A framework to evaluate and elucidate the driving mechanisms of coastal sea surface pCO2 seasonality using an ocean general circulation model (MOM6-COBALT)

Roobaert A., Resplandy L., Laruelle G. G., Liao E. and Regnier P.

The temporal variability of the sea surface partial pressure of CO2 (pCO2) and the underlying processes driving this variability are poorly understood in the coastal ocean. In this study, we tailor an existing method that quantifies the effects of thermal changes, biological activity, ocean circulation and freshwater fluxes to examine seasonal pCO2 changes in highly variable coastal environments. We first use the Modular Ocean Model version 6 (MOM6) and biogeochemical module Carbon Ocean Biogeochemistry And Lower Trophics version 2 (COBALTv2) at a half-degree resolution to simulate coastal CO2 dynamics and evaluate them against pCO2 from the Surface Ocean CO2 Atlas database (SOCAT) and from the continuous coastal pCO2 product generated from SOCAT by a two-step neuronal network interpolation method (coastal Self-Organizing Map Feed-Forward neural Network SOM-FFN, Laruelle et al., 2017). The MOM6-COBALT model reproduces the observed spatiotemporal variability not only in pCO2 but also in sea surface temperature, salinity and nutrients in most coastal environments, except in a few specific regions such as marginal seas. Based on this evaluation, we identify coastal regions of “high” and “medium” agreement between model and coastal SOM-FFN where the drivers of coastal pCO2 seasonal changes can be examined with reasonable confidence. Second, we apply our decomposition method in three contrasted coastal regions: an eastern (US East Coast) and a western (the Californian Current) boundary current and a polar coastal region (the Norwegian Basin). Results show that differences in pCO2 seasonality in the three regions are controlled by the balance between ocean circulation and biological and thermal changes. Circulation controls the pCO2 seasonality in the Californian Current; biological activity controls pCO2 in the Norwegian Basin; and the interplay between biological processes and thermal and circulation changes is key on the US East Coast. The refined approach presented here allows the attribution of pCO2 changes with small residual biases in the coastal ocean, allowing for future work on the mechanisms controlling coastal air–sea CO2 exchanges and how they are likely to be affected by future changes in sea surface temperature, hydrodynamics and biological dynamics.

link to the article

Nature Geoscience - October 2021

End-permian marine extinction due to temperature driven nutrient recycling and euxinia

Hülse D., Lau K.V., van de Velde S.J., Arndt S., Meyer K.M. and Ridgwell A.

Extreme warming at the end-Permian induced profound changes in marine biogeochemical cycling and animal habitability, leading to the largest metazoan extinction in Earth’s history. However, a causal mechanism for the extinction that is consistent with various proxy records of geochemical conditions through the interval has yet to be determined. Here we combine an Earth system model with global and local redox interpretations from the Permian/Triassic in an attempt to identify this causal mechanism. Our results show that a temperature-driven increase in microbial respiration can reconcile reconstructions of the spatial distribution of euxinia and seafloor anoxia spanning the Permian–Triassic transition. We illustrate how enhanced metabolic rates would have strengthened upper-ocean nutrient (phosphate) recycling, and thus shoaled and intensified the oxygen minimum zones, eventually causing euxinic waters to expand onto continental shelves and poison benthic habitats. Taken together, our findings demonstrate the sensitive interconnections between temperature, microbial metabolism, ocean redox state and carbon cycling during the end-Permian mass extinction. As enhanced microbial activity in the ocean interior also lowers subsurface dissolved inorganic carbon isotopic values, the carbon release as inferred from isotope changes in shallow subsurface carbonates is likely overestimated, not only for this event, but perhaps for many other carbon cycle and climate perturbations through Earth’s history.

link to the article

Global Biogeochemical Cycles - July 2021

Global uptake of atmospheric methane by soil from 1900 to 2100.

Murguia-Flores F., Ganesan A.L., Arndt S. and Hornibrook R.C.

Soil methanotrophy is the only biological process that removes CH4 from the atmosphere. There is good agreement about the size of the global sink but great uncertainty about its interannual variability and regional responses to changes in key environmental drivers. We used the process-based methanotrophy model MeMo v1.0 and output from global climate models to simulate regional and global changes in soil uptake of atmospheric CH4 from 1900 to 2100. The annual global uptake doubled from 17.1±2.4 to 37.2±3.3 Tg yr-1 from 1900-2015 and could increase further to 82.7±4.4 Tg yr-1 by 2100 (RCP8.5), primarily due to enhanced diffusion of CH4 into soil as a result of increases in atmospheric CH4 mole fraction. We show that during the period 1980-2015 temperature became an important influence on the increasing rates of soil methanotrophy, particularly in the Northern Hemisphere. In RCP-forced simulations the relative influence of temperature on changes in the uptake continues to increase, enhancing the soil sink through higher rates of methanotrophic metabolic activity, increases in the global area of active soil methanotrophy and length of active season. During the late 21st century under RCP6.0, temperature is predicted to become the dominant driver of changes in global mean soil uptake rates for the first time. Regionally, in Europe and Asia, nitrogen inputs dominate changes in soil methanotrophy, while soil moisture is the most important influence in tropical South America. These findings highlight that the soil sink could change in response to drivers other than atmospheric CH4 mole fraction.

link to the article

New publication in NATURE

New publication in NATURE

The land-to-ocean loops of the global carbon cycle

Regnier P., Resplandy L., Najjar R.G. and Ciais P.

Nature: link

Communiqué de presse (FR): link

Carbon storage by the ocean and by the land is usually quantified separately, and does not fully take into account the land-to-ocean transport of carbon through inland waters, estuaries, tidal wetlands and continental shelf waters—the ‘land-to-ocean aquatic continuum’ (LOAC). Here we assess LOAC carbon cycling before the industrial period and perturbed by direct human interventions, including climate change. In our view of the global carbon cycle, the traditional ‘long-range loop’, which carries carbon from terrestrial ecosystems to the open ocean through rivers, is reinforced by two ‘short-range loops’ that carry carbon from terrestrial ecosystems to inland waters and from tidal wetlands to the open ocean. Using a mass-balance approach, we find that the pre-industrial uptake of atmospheric carbon dioxide by terrestrial ecosystems transferred to the ocean and outgassed back to the atmosphere amounts to 0.65 ± 0.30 petagrams of carbon per year (±2 sigma). Humans have accelerated the cycling of carbon between terrestrial ecosystems, inland waters and the atmosphere, and decreased the uptake of atmospheric carbon dioxide from tidal wetlands and submerged vegetation. Ignoring these changing LOAC carbon fluxes results in an overestimation of carbon storage in terrestrial ecosystems by 0.6 ± 0.4 petagrams of carbon per year, and an underestimation of sedimentary and oceanic carbon storage. We identify knowledge gaps that are key to reduce uncertainties in future assessments of LOAC fluxes.

Publication in Frontiers for Young Minds

Publication in Frontiers for Young Minds

 

Frontiers for Young Minds is a spin off of the traditional per-review journals which is dedicated to kids. The idea is to write a more broadly accessible article about scientific research which is then reviewed by children with their own eyes and knowledges.

This interesting exercise was experienced by BGEOSYS related scientists by the publication of “Virtual Reality: Using Computer Models to Learn About Arctic Climate Change“.

A very nice initiative which will perhaps arouse vocations.

Citation: Ward J, Freitas F, Hendry K and Arndt S (2020) Virtual Reality: Using Computer Models to Learn About Arctic Climate Change. Front. Young Minds. 8:125. doi: 10.3389/frym.2020.00125

August 2020 “Science Advances”

August 2020 “Science Advances”

Widespread energy limitation to life in global subseafloor sediments

J.A. Bradley, S. Arndt, J. P. Amend, E. Burwicz, A. W. Dale, M. Egger and D. E. LaRowe

ABSTRACT

Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth’s biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation and calculate the power utilization of microbial cells throughout Earth’s Quaternary-age subseafloor sediments. Aerobic respiration, sulfate reduction, and methanogenesis mediate 6.9, 64.5, and 28.6% of global subseafloor organic matter degradation, respectively. The total power utilization of the subseafloor sediment biosphere is 37.3 gigawatts, less than 0.1% of the power produced in the marine photic zone. Aerobic heterotrophs use the largest share of global power (54.5%) with a median power utilization of 2.23 × 10−18 watts per cell, while sulfate reducers and methanogens use 1.08 × 10−19 and 1.50 × 10−20 watts per cell, respectively. Most subseafloor cells subsist at energy fluxes lower than have previously been shown to support life, calling into question the power limit to life.

https://advances.sciencemag.org/content/advances/6/32/eaba0697.full.pdf

Publication in “Science” August 2019

Publication in “Science” August 2019

The geologic history of seawater oxygen isotopes from marine iron oxides

Galili N., Shemesh A., Yam R., Brailovsky I., Sela-Adler M., Schuster E.M., Collom C., Bekker A., Planavsky N., Macdonald F.A., Préat A., Rudmin M., Trela W., Sturesson U., Heikoop J.M., Aurell M., Ramajo J. and Halevy I.

https://science.sciencemag.org/content/365/6452/469

Abstract

The oxygen isotope composition (δ18O) of marine sedimentary rocks has increased by 10 to 15 per mil since Archean time. Interpretation of this trend is hindered by the dual control of temperature and fluid δ18O on the rocks’ isotopic composition. A new δ18O record in marine iron oxides covering the past ~2000 million years shows a similar secular rise. Iron oxide precipitation experiments reveal a weakly temperature-dependent iron oxide–water oxygen isotope fractionation, suggesting that increasing seawater δ18O over time was the primary cause of the long-term rise in δ18O values of marine precipitates. The 18O enrichment may have been driven by an increase in terrestrial sediment cover, a change in the proportion of high- and low-temperature crustal alteration, or a combination of these and other factors.

ARC Project: NuttI

ARC Project: NuttI

Nutrient Factories under the Ice (NuttI): Quantifying the subglacial biogeochemical reactor and its response to climate change

Prof. Sandra Arndt as coordinator (BGeoSys) and Prof. Frank Pattyn (Laboratoire de Glaciologie), are funded for their "Actions de Recherche Concertée-ARC" project: NuttI.

Climate change is amplified in polar regions. As a consequence, ice sheets and glaciers (and in particular the Greenland Ice Sheet) are currently experiencing record melting, resulting in a significant increase of already substantial summer freshwater fluxes to the ocean. While the physical consequences of this freshwater input, as well as its alarming increase have been intensively studied, its biogeochemical dimension remains poorly understood.

The specific objectives of NuttI are to:

  1. develop and test the very first, mechanistic, hydrological-biogeochemical model framework for subglacial environments and, thus, provide novel analytic and predictive capabilities for assessing the consequences of ice sheet retreat
  2. use the newly developed model to quantitatively identify the main hydrological and biogeochemical controls on subglacial carbon and nutrient export under different environmental conditions and over a melt season

More information on NuttI

Cruise in the Baltic Sea: study of the effects of hypoxia

Cruise in the Baltic Sea: study of the effects of hypoxia

From the 18th of June to the 5th of July, Prof. Lei Chou, Nathalie Roevros, Audrey Plante and Hailong Zhang participated to an oceanographic cruise on board of the R.V. BELGICA in the Baltic Sea near Gotland Island. This was organised in collaboration with Prof. Martine Leermakers from the Department of Analytical, Environmental and Geochemistry (AMGC) at the Vrije Universiteit Brussel (VUB).

The deep waters of this area are often hypoxic which have a great influence on the biogeochemical conditions of the water column and sediments.

The objectives are to understand benthic nutrient and trace metal cycling, benthic‐pelagic coupling, diagenetic pathways and the impact of hypoxia on these processes.